In a lithography process for manufacturing microdevices such as semiconductor devices (integrated circuits and the like) and liquid crystal display devices, besides an exposure process in which a predetermined pattern is formed on a substrate such as a wafer or a glass plate (hereinafter, generally referred to as a ‘wafer’) using an exposure apparatus, processes, which are performed before or after the exposure process, such as a resist coating process in which resist is coated on the surface of the wafer and a development process in which the wafer after exposure is developed are included.
Conventionally, in a lithography process, exposure by an exposure apparatus, resist coating by a resist coating unit (coater), development of a wafer using a developing unit (developer) and the like were performed separately. In recent years, in order to efficiently perform the exposure, resist coating and development described above as a series of processing in a clean environment, a system configuration in which an exposure apparatus and a coating/developing unit that is called a coater/developer (hereafter, shortened to a ‘C/D’) are inline connected has been relatively frequently employed. The C/D has both of a function of a resist coating unit such as a spin coater that falls drops of resist on a wafer while rotating the wafer at high speed and uniformly coats the resist on the wafer surface making use of rotation of the wafer, or a scan coater that relatively moves a nozzle and the wafer, and a function of a developing unit.
Accordingly, with the system configuration above, complication of loading a processing lot (a lot of wafers subject to processing) when each processing process such as the resist coating process, exposure process or development process is performed can be avoided, and in addition, throughput can be improved while maintaining chemical characteristics of chemically-amplified resist that is a type of high sensitive resist and has recently been frequently used, or the like.
Meanwhile, in order to improve the productivity of microdevices, the demand for improvement (increase) in an operating rate (uptime) with respect to the exposure apparatus is always existing. In order to meet the demand, efforts to decrease apparatus failure have also been continued. To decrease the failure, periodic maintenance is also important.
The demand for operating rate improvement of an exposure apparatus or the like is increasing year by year, and at present it is desired to achieve an operating rate of 95% or more.
However, it is not easy to achieve an operating rate of 95% or more even in the case of the exposure apparatus alone. The reason is that the demand for accuracy improvement and stabilization of a high accuracy state of the exposure apparatus is also increasing, to cope with higher integration of semiconductor devices. In other words, in order to meet the demand for exposure accuracy improvement and stabilization of a high accuracy state of the exposure apparatus, it becomes necessary to increase the frequency of periodic maintenance and also enhance self-calibration function of the exposure apparatus, which could increase, however, downtime of the exposure apparatus when a requested level becomes higher than a certain level.
Accordingly, in the system in which the exposure apparatus and the C/D are inline connected (hereinafter, referred to as an ‘inline lithography system’), it can be said that it is extremely difficult to achieve an operating rate of 95% in the present situation. This is because in the inline lithography system, in the case the operation of the C/D is stopped for periodic maintenance, component replacement, or other reasons, the operation of the exposure apparatus has to be also stopped, and therefore, there are more factors to reduce an operating rate of the exposure apparatus, compared with the case of the exposure apparatus alone.